• • Flash Joule heating (FJH) achieves atomically dispersed Cu on TiO2 within milliseconds, bypassing thermodynamic aggregation; Cu1.0/TiO2 exhibits ~10-fold enhancement in CO evolution over pristine TiO2 under simulated solar irradiation, demonstrating superior photocatalytic performance.
• • HAADF-STEM and XAFS confirm the atomic dispersion and robust metal–support interaction, validating the stability of Cu ADMs against sintering, a critical factor for long-term catalytic operation.
• • In-situ DRIFTS and photoelectrochemical measurements reveal that isolated Cu sites act as electron-trapping centers, accelerating interfacial charge transfer and promoting CO2 activation, which is essential for efficient solar fuel production.
• • The FJH method offers a scalable, ultrafast synthesis route for stable ADM-decorated photocatalysts, overcoming the stability-dispersion trade-off that limits conventional wet-chemistry or thermal calcination approaches.